One of the biggest worries that homeowners have about their central heating is that it will stop working. If there are noises, leaks, worn parts, or even if your central heating does cease altogether; don't panic. Sometimes a big noise can be caused by a small fault. If you can trace the problem to its cause, you may find that you can fix the problem yourself without having to involve the costs and time of calling a heating engineer.
Dripping Overflow Pipe
The overflow pipe leads from the feed/expansion tank outside through the wall or roof, and allows the water to escape if the tank gets too full. If the ballcock does not fully shut off the tank's valve, water will continue to flow and cause overspill out of the pipe. In this instance, the float valve itself may be damaged or the washer could have worn.
Both these items can be purchased from a DIY hardware store or plumbers merchant. To replace them, turn off the cold water supply to the tank and remove enough water with a bucket to enable you to install the replacements.
Leaking joints and valves
Joints that are soldered will require full replacement if they leak. Before carrying out any repairs, always drain the heating system.
Leaks on compression joints are often remedied by tightening the nut. As you tighten it, hold the other nut in place with a spanner or wench to prevent any movement. Only tighten the joint around a quarter turn or else you will put the joint under further strain. If this does not cure the leak, you will need a drain and replacement.
If the leak is located on the side of the valve toward the radiator, you will only need to turn off both valves and drain the offending radiator as opposed to the whole system. Once the joint is disconnected, wind some PTFE tape around it and re-insert. This should prevent further leakage. Following this, open the air vent and the flow valve to fill the radiator, closing the vent when water starts to come out. Now you can open the return valve. Similar joints can be treated in a similar method.
The valve body may spring a leak where the nut at the bottom of the spindle becomes loose. Use one spanner to hold the vale body still, and another to gently tighten the nut. If this fails, it indicates that the gland packing for the nut is worn. With both valves off, undo the gland nut and wind some gland packing around the base, poking it in securely with a screwdriver. The nut will require replacing and tightening before opening one valve at a time and checking for leaks.
Noisy Heating Pipes
It is often the case that noises in the central heating system are caused by air trapped somewhere. As well as causing a cacophony of sounds, trapped air can lead to corrosion of radiators and the boiler. To prevent this, fit a de-aerator to the vent pipe. A de-aerator is like a copper bottle that causes turbulence to get the air out of the system.
Gurgling Heating System: Watery gurgles are certainly caused by trapped air. To remedy this, turn off the central heating and bleed the radiators.
Humming Central Heating: This may be due to the pump. It will cause a loud vibration if it is set too fast, so try turning it to a lower setting. Alternatively, the pump may be vibrating the pipes, in which case you can mount the pump onto brackets that absorb the vibrations. If this is still to no avail, it may be that the pipes themselves are too small for the amount of water trying to pass through.
Knocking/creaking: As the water heats up, the pipes expand, and then contract again as they cool. If there is not enough space to allow for the movement of the pipes it will cause noises under the floorboards or in the walls. If the rubbing is occurring by the joists, cut a little wood away on one side; do not cut too much or this will weaken the joist. Padding some insulation around the pipe will also prevent the rubbing noise.
If the pipes have plenty of room but are still knocking, then they probably have inadequate support. Loose moving pipes will need securing by a small batten screwed between the joists held in place with pipe clips.
Water Hammer: Turning taps and opening valves sharply on and off stop the water rapidly, and can cause a reverb along the pipes. As the wave bounces down the pipes this turns into a banging, hammering noise. There are several possible reasons for this:
- Water flow too fast for pipes to handle
- Stopcock impeded by loose packing and worn out jumpers
- Taps have loose packing and worn out jumpers
- Ball valve in cold water storage tank faulty
Other instances can be solved by installing a shock absorber in the mains system.
Boiler noises can again be the result of trapped air. Another reason may be as a result of the build up of sludge and scale which causes hotter areas leading to steam pockets within the unit. The sludge will also inhibit the water flow and so cause noise as the water tries to force through. To clear the debris, add a non-acidic cleaner and descaler into the feed/expansion tank and drain a few days later.
The boiler may strain if there is a lack of water flowing. Have a look at the feed and expansion tank to ensure that it is topping up when the ballcock opens. If not, this can indicate that the mains is switched off, that there is an air lock, or there is a frozen pipe.
Make sure that the water flow rate is correct. If the water flow is inadequate that boiler will create noise. This can be an issue particularly with wall hung boilers.
No hot water/heating
- Check that the power is on and that it has not blown a fuse. If it has, find out why the fuse has blown
- Check that the oil or gas supply has not been turned off, or in the case of oil, look at the gauge to make sure there is some
- Check that the programme timer is on, and the thermostats are turned up enough
- Check that the pump is running
- Check the pilot light is lit
If all else fails, contact a heating engineer.